Crystallizable polymers of t-butyl acrylate and methacrylate



' drocarbon solvent.

United States Patent 3,177,186 CRYSTALLIZABLE POLYMERS F t-BUTYL ACRYLATE AND METHACRYLATE Mary Lucy Miller, New York, N.Y., assignor to American Cyanamid. Company, Stamford, Conn., a corporation of Maine No Drawing. Filed June 7, 1963, Ser. No. 286,203 6 Ciaims. (Cl. 260-895) This invention relates to the preparation of crystallizable polyesters. More specifically, the present invention relates to a novel process for preparing crystallizable polymers of tertiary butyl acrylate and tertiary butyl methacrylate and to a procedure for production of crystalline poly(acrylic acid) by the further treatment of the acrylate polymers.

Briefly, the invention comprises the preparation of polymers having an ordered molecular arrangement characteristic of crystallinity by reacting monomers of the group consisting of tertiary butyl acrylate and tertiary butyl methacrylate in the presence of n-butyl lithium as a catalyst. The crystallizable polymer obtained may crystallize during the course of polymerization or it may subsequently be converted to the solid crystalline polymer by suitable treatment with agents like acetone, In

1 a further aspect, the ester group of the crystallizable polymers of tertiary butyl acrylate or tertiary butyl methacrylate may be converted to acid groups to form crystallizable polyacrylic acid or polymethacrylic acid, respectively. This may be accomplished, for example, by deproduce the corresponding polyesters which differ from the polyester initially prepared.

It is an object of the present invention to provide a novel method for preparing crystallizable and crystalline polymers of tertiary butyl acrylate and tertiary butyl methacrylate. It is still another object of the invention to provide a method of making crystallizable polymers wherein crystallizable polymers of this group prepared according to the invention are employed as intermediates. It is a further object of the instant invention to provide a method for the production of crystalline poly- (acrylic acid). Other objects and advantages will become apparent to those skilled in the art upon reading the more detailed description of the invention set forth hereinbelow. V

In carrying out the process, the ester monomer, in a' pure state, is introduced into a suitable vessel and mixed together with n-butyl lithium as a catalyst. The catalyst is preferably introduced-as a solution in a suitable hy- According to my discovery, the nbutyl lithium catalyst may be employed alone or it may be employed in conjunction with .a fine dispersion of metallic lithium, the procedure for the preparation and the technique for the use of which is described in my U.S; Patent No. 3,088,939. In some instances, for example, where the reaction has been contaminated, the presence of n-butyl lithium in combination with metallic lithium dispersion as cocatalysts isadvantageous and is preferred over the use of lithium alone.

An inert atmosphere is maintained throughout the polymerization reaction. The. polymerization occurs gradually and is allowed to proceed to a substantially "ice solid phase. If desired, the polymerization system may utilize a suitable liquid medium which preferably behaves as a solvent for the monomer. However, a solvent is not necessary as polymerization of the monomer to the ordered structural arrangement of crystallinity occurs in the presence of the n-butyl lithium and the small amounts of solvent therefor which may be present.

The n-butyl lithium employed as the catalyst in the present invention may be obtained commercially or it may be prepared by the reaction of n-butyl chloride with lithium metal. Based on the weight of the monomeric compound, amounts of from about 0.01% to about 5% by weight of the catalyst may be employed although an amount of from about 0.05% to about 1.0% by weight is more satisfactory and is preferably used. As noted hereinabove, the catalyst is preferably employed in solution in any one of various substantially inert organic solvents such as hexane, heptane, petroleum ether, and the like.

A substantial proportion of the polymer which forms has a crystallizable or ordered molecular structural arrangement as distinguished from an amorphous polymer of random molecular arrangement in which there is little or no order in the mannerin which the molecules are arranged.

I have discovered that n-butyl lithium has the unexpected'capacity to form crystalline polymers of tertiary butyl acrylate and tertiary butyl methacrylate, i.e. polymers which have a predominant number of the monomer unitsin the polymer structure or chain arranged in a regular repeating configuration. This property is not obtained with free radical type catalysts.

As mentioned heretofore, the process of the present invention may employ the monomer alone with n-butyl lithium dispersions dissolved in a small amount of solvent or the system may utilize a polymerization medium which ispreferably a solvent for the monomer. When a polymerization medium is utilized, it is necessary that it be inert to the polymerization reaction taking place. Among the solvents which may be 'used advantageously are hexane, heptane, octane, or other aliphatic solvents having from 4 to 10 carbon atoms, for example, or mixtures thereof, and various other available compounds known to be substantially inert, such as petroleum ether.

.The amount of solvent, when used, is not critical and may vary in amounts up to or more of the weight of the monomer although practical limitations are generally imposed on amounts exceeding about 75% by Weight of the monomer. It will be apparent that the amount of solvent will be governed by the amount of solids content of polymeric material desired therein. These solvents may be'used either singly or in combination with one another. In the practice of the process of the present invention, the conditions of reaction may be varied rather extensively. For example, one may utilize temperatures from about C. up to about room temperature. At the temperatures in the upper part of the range, to avoid excess exotherm, it is necessary to add the catalyst at a slow rate. Consequently, it is desired as a practical matter to avoid higher temperatures. The preferred temperature range is between about 0 C. and about 70. C. Pressure is not a critical factor in carrying out the instant process inasmuch as atmospheric pressure, super-atmospheric pressure or sub-atmospheric pressure may be utilized. As a practical matter, atmospheric pressure is preferred. 1 I

' Following polymerizatiomthe crystalline polymer may be isolated by extracting the polymeric material with a compound which is a solvent for the noncrystalline polymerbut at the same time a nonsolventfor the crystalline polymer. An example of such a solvent is acetone. It will be apparent that for some uses, the separation of the crystalline polymer from the amorphous polymer formed therewith may not benecessaryor desirable.

- polymer purity is desired the addition of a small amount of alcohol, e.g. methanol, as a part of the solvent or as Where high extracted twicewithcold acetone and twice with hot acetone- The acetone'insoluble polymer, from; to 45% a precipitant for the polymer-will destroy the unused catalyst, g

The crystallizablepolymer of tertiary butyl acrylate is as an intermediate in the preparation of derivatives thereof the total isgcrystallineas shownby X-rayu The fraction of the polymer which is soluble in hotacetone contains minor'amounts of: crystallinity. Although equal quantities of tertiary butyl acrylate and hexane are em a highly useful resinous composition. It is also valuable ployed in the foregoing. example, the monomer to hexane mixture may range from 100% monomerto 90% hexane.

of. For example, polyacid derivatives of tertiary butyl i acrylate maybe obtained by hydrolyzing the crystallizable or crystalline polymer containing the ester groups inan acid medium within a wide temperature range, e.g. be tween about C. and 210 C. This reaction decomposes the ester groups of the polymerto produce acrylic acid groups, i.e to form .crystallizable polyacrylic acid which is also a highly useful resinous material; Is'obutylene gas is evolved in the reaction. Additionally, the crysas an intermediate in the'preparation of a diiferent crystallizable. polymeric ester, for'example, polymethacrylate or polyethacr'ylate and the like, by esterifying the crystallizable polyacrylic'acid. This esterification may be accomplished, for example, by' refluxing the polyacrylic acid with an excess of a suitable alcohol, methyl, ethyl, propyl or isopropyl alcoholin the presence of anacid, such as sulfuric acid, hydrochloric acid, acetic acid, propionic acid, p-toluene'sulfuric acid, and the like. The reaction product, when the crystallizable polyacrylic acid intermediate is utilized, is crystallizable poly-n-butyl acrylate.

crystallizable esters by a similar procedure which results in transesterification. 'In a like manner, poly-tertiary butyl methacrylate produced according to the invention may bepost-treated in similar chemical reactions which do not break the ,C-CC chain of the polymer 1 backbone to producecorresponding products.

The modification of these polymers without loss in their crystallizable property is possible because the ordered arrangement in the polymer which makes crystallization possible resides in the -CCC- linkagesof the back: bone with respect to the side group orientation. Therefore, any reaction on the side groups that does not break not destroy the ability of the polymer to crystallize. Each. of'the crystallizable polymers derived from tertiary butyl The poly(tert.-butyl esters) canalso be converted toother f I tallizable .polyacrylicacid so produced may be employed Initial temperatures of the order of 0 to; 80 C. are preferred because ofthe exotherm'of the reaction. Room tern erature is satisfactory at latergstages of the reaction.

, EXAMPLE 2 then extractedtwice with cold acetone-and twicewith warm acetone. The. portion of the :polymer which is insoluble in the. acetone.'.(40%) is subjected to X-ray analysis. Measurable [l-spacings' indicative 'of crystal linity are observed. I

" EXAMPLE 3 cc. of hexane, and 20 cc. of pure dry tertiary butyl acrylate are mixed and approximately 100- milligrams of lithium (ass. 24% dispersion in petrolatum) is added. The mixture is allowed to stand at room'temperature 20 hours. It is then cooled to 70 C. and 1' cc. of a 15% solution of n-butyl lithiumjin petroleum ether added.

After 2 hours at +70 C.', the contents ofthe' flask are' solid with polymer. Thepolyrner is extracted2 times 7 with a boling 1:1 mixture of methanol and acetone to rethe CCC linkages of the polymer. backbone will acrylate and tertiary butyl. methacrylate, as well asthe crystallizable polymers derived from the further modification of these polymers, are highly useful resinous com,-

Theyfind application and applicability, for

positions. example, as adhesives, molding compositions, laminatingcompositions, in fiber forming or in the treatment of various materials, such as textiles which are made ,up i either of natural or syntheticfibers including wool,'line'n,'

cotton, nylon and other synthetics or in the treatment of 1 paper or paper pulp, wood or leather.

. The following examples are setforth for purposes/of illustration only'and are not to be construed as limitations on the present invention except as set forthin the appended claims. ,All parts andpercentages are by weight i unlessotherwiseindicated.

7 EXAMPLE: 1

Equal quantities of pure tertiary butyl acrylate and hexane are introduced into a suitable reaction vessel-and mixedin a dry, oxygen-free atmosphere; The mixtureis cooled to C. in a Dry Ice-butanol mixture. A solution 'of n-butyl lithium in a hydrocarbon medium (petro- 1 leum ether) is added. 0.5,percent, by weight, of catalyst 'is used, although-from about .0;O2% to 1% by Weight.

vbased on monomer, is a convenient amount of catalyst.

1 A gelatinous precipitate appears at onceg'more forms over the next houra Onwar'mingto room-temperature, the.

contents ofthe vessel are solid. The polymer is slurried with a methanohacetone mixture (1:1) twice; It is then move catalyst; The polymer is then extracted 3' times with boilingacetone .to remove any amorphous polymer present. About 40% of thetotal polymer is found insoluble in boiling acetone and gives a crystalline X-ray diffraction pattern. T i

EXAMPLES 4-10 Purified monomers are dried over calcium hydride and (listilledto a recovery tube containing twice their volume of dry hexane. The tubes are sealed, cooled to -70 C. and;a volume of n-butyl lithium solution (15% in petroleumether) equal to approximately iyof the volume. of themonomer added. The polymer which forms is worked up as .iniExample-2- andsubinitted to examination by Xray diffraction. The rnonomers employed and the character of the polymer obtained are setforth below 1 in Table I.

v Table I 1' Example Monomer; 7 Results Cyclohexyl acrylate- .Non-crystalline polymer.

' n-Butyl acrylate Gummy polymer; Isobutyl aerylate -Do.

See. butyl acrylate Benzyl acrylate.

vNori-crys'talline polymer.

Styrene D0,; 1' tButyl acrylate -J.-- V Crystalline polymer.

To li p a'rts of the fcrystalline.poly(t-butyl acrylate) produced in Exarmple l, are added- 300 parts-of dioxane.

The .rnixture is-pla'ced in afsuitable vessel and allowed *to, refiuxyior '1. hour. Twenty-five parts-of concentrated hydrochloric acid and'zl-O parts of water, a-rethen added and the resultant mixture is then'refluxed" for 18 hours. Poly(acrylic acid) is recovered and zwhen subjected to X-ray analysis, exhibits clear, dark, measurable d-spacings indicating that the polymer is crystalline.

EXAMPLE 12 Fifteen (15) parts of the hot acetone soiuble portion of the poly(t-butyl acrylate) (i.e. the crystallizable portion) produced in Example 1 are treated according to the procedure of Example 11. The resultant crystallizable poly-acrylic acid), upon setting alone for 24 hours, becomes crystalline as evidenced by the observation of measurable d-spacings when the polymer is subjected to X-ray analysis.

This application is a -continuation-in-part of my abandoned application Serial No. 761,290, filed September 16, 1958.

I claim:

1. A method of preparing a crystalline homopolymer comprising mixing a monomeric compound selected from the group consisting of tertiary butyl acrylate and tertiary butyl methacrylate with a catalyst consisting essentially of a substantially inert organic solvent solution of nbutyl lithium in amounts ranging from about 0.01% to 5.0%, by weight, based on the weight of said monomeric compound, polymerizing the resultant mixture at a temperature ranging from about 90 C. to about room temperature in an inert atmosphere and separating the resultant crystalline polymeric product. I

2. The method of claim 1 wherein the monomeric compound is dissolved in an organic medium which is a solvent for said compound, said medium being selected from the group consisting of aliphatic solvents having from 4-10 carbon atoms and petroleum ether.

3. A method of preparing a crystalline homoploymer comprising mixing a monomeric compound consisting essentially of tertiary butyl acrylate with a catalyst system consisting essentially of a substantially inert organic solvent solution of n-butyl lithium in amounts ranging,

from about 0.05% to 1.0%, by weight, based on the weight of said monomeric compound, polymerizing the resultant mixture at a temperature ranging from about --90 C. to about room temperature in an inert atmosphere and separating the resultant crystalline polymeric product.

4. A method of preparing a crystalline homopolymer comprising mixing a monomeric compound consisting essentially of tertiary butylmethacrylate with a catalyst system consisting essentially of a substantially inert organic solvent solution of n-butyl lithium in amounts ranging from about 0.05% to 1.0%, by weight, based on the Weight of said monomeric compound, polymerizing the resultant mixture at a temperature ranging from about C. to about room temperature in an inert atmosphere and separating the resultant crystalline polymeric product.

5. A method of preparing crystallizable poly(acrylic acid) which comprises mixing a monomeric compound consisting essentially of tertiary butyl acrylate with a catalyst system consisting essentially of a substantially inert organic solvent solution of n-butyl lithium in amounts of from about 0.05% to about 1.0%, by Weight, based on the weight or" said monomeric compound, polymerizing the resultant mixture at a temperature ranging from about 90 C. to about room temperature in an inert atmosphere, separating the resultant crystallizable reaction product, and hydrolyzing said reaction product in an acid medium at a temperature ranging from about 20 C. to about 210 C. until the ester groups of said polymeric reaction product are substantially decomposed to carboxyl groups.

6. A method of preparing crystalline poly(acrylic acid) which comprises mixing a monomeric compound consisting essentially of tertiary butyl acrylate with a catalyst system consisting essentially of a substantially inert organic solvent solution of n-butyl lithium in amounts of from about 0.05% to about 1.0%, by weight, based on the weight of said monomeric compound, polymerizing the resultant mixture at a temperature ranging (from about -90 C. to about room temperature in an inert atmosphere, separating the resultant crystalline reaction product, and hydrolyzing said reaction product in an acid medium at a temperature ranging from about 20 C.,to about 210 C. until the ester groups of said polymeric reaction product are substantially decomposed to carboxyl groups.

References Cited by the Examiner UNITED STATES PATENTS 3/61 Schuller 260--88.7 5/63 Miller 26089.5 

1. A METHOD OF PREPARING A CRYSTALLINE HOMOPOLYMER COMPRISING MIXING A MONOMERIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF TERTIARY BUTYL ACRYLATE AND TERTIARY BUTYL METHACRYLATE WITH A CATALYST CONSISTING ESSENTIALLY OF A SUBSTANTIALLY INERT ORGANIC SOLVENT SOLUTION OF NBUTYL LITHIUM IN AMOUNTS RANGING FROM ABOUT 0.01% TO 5.0%, BY WEIGHT, BASED ON THE WEIGHT OF SAID MONOMERIC COMPOUND, POLYMERIZING THE RESULTANT MIXTURE AT A TEMPERATURE RANGING FROM ABOUT -90*C. TO ABOUT ROOM TEMPERATURE IN AN INERT ATMOSPHERE AND SEPARATING THE RESULTANT CRYSTALLINE POLYMERIC PRODUCT. 